PRAIRIE FARMER'S POULTRY BOOK 



converting it into the substances which make up the or- 

 ganism ; and oxidation, a process by which cell substances and 

 organic compounds in the blood are united with oxygen, pro- 

 ducing heat and energy; and excretion, by which the waste 

 matter is thrown off from the body. 



These processes have been studied to some extent in Chap- 

 ter II. Our discussion here pertains more especially to 

 digestion, assimilation and oxidation. 



Another Practical Lesson 



It has been pointed out that the albumin and other proteids 

 of the food are changed into peptone by the gastric juice and 

 this is carried by the portal circulation to the liver where it 

 is changed back to albumin. The gastric juice secreted by the 

 stomach and gizzard contains three digestive principles-^hy- 

 drochloric acid, pepsin and rennin. The rennin coagulates 

 the albumin and the pepsin changes it to peptone, but this 

 process cannot be carried on without the aid of the hydro- 

 chloric acid. 



Now the hydrochloric acid is manufactured from the salt 

 which is found in the blood. This suggests the importance 

 of feeding salt in the daily ration. Its aid to digestion is here 

 indicated. 



Another digestive process is the change in the carbohy- 

 drates (starches and sugars) to glucose. This is also trans- 

 ported to the liver and there converted into glycogen, which is 

 taken up by the blood. 



Still another change in the food is accomplished by the 

 pancreatic and intestinal juices by which the fats are saponi- 

 fied and emulsified so that they can be taken into the lymphatic 

 circulation and by this emptied into the general circulation. 



What Becomes o£ Digested Food? 



The emulsified fat is oxidized in the lungs, producing heat 

 and energy. It is probably all oxidized, as very little is found 

 in the blood after it leaves the lungs. It is not used to make 

 fatty tissue. That is made from the other elements of the 

 food in the body itself. , 



The glycogen, representing the carbohydrate of the food, is 

 oxidized in the blood. It is the great source of heat and 

 energy. Not all is oxidized there, but a portion of it goes to 

 the cells and is used to manufacture fat. 



[29] 



